All these principles must be applied to the sixteenth-century _a capella_ music. In fact, there is no better illustration; its meaning and effect cannot be otherwise understood. Growing up under what seem perfectly natural conditions, patronized by the laity as well as by the clergy, this highly organized, severe, and impersonal style was seen, even before the period of its maturity, to conform to the ideal of liturgic art cherished by the Church; and now that it has become completely isolated in the march of musical progress, this conformity appears even more obvious under contrast. No other form of chorus music has existed so objective and impersonal, so free from the stress and stir of passion, so plainly reflecting an exalted spiritualized state of feeling. This music is singularly adapted to reinforce the impression of the Catholic mysteries by reason of its technical form and its peculiar emotional appeal. The devotional mood that is especially nurtured by the Catholic religious exercises is absorbed and mystical; the devotee strives to withdraw into a retreat within the inner shrine of religious contemplation, where no echoes of the world reverberate, and where the soul may be thrilled by the tremulous ecstasy of half-unveiled heavenly glory. It is the consciousness of the nearness and reality of the unseen world that lends such a delicate and reserved beauty to those creations of Catholic genius in which this ideal has been most directly symbolized. Of this cloistral mood the church music of the Palestrina age is the most subtle and suggestive embodiment ever realized in art. It is as far as possible removed from profane suggestion; in its ineffable calmness, and an indescribable tone of chastened exultation, pure from every trace of struggle, with which it vibrates, it is the most adequate emblem of that eternal repose toward which the believer yearns. It is not true, however, as often alleged, that this form of music altogether lacks characterization, and that the style of Kyrie, Gloria, Crucifixus, Resurrexit, and of the motets and hymns whatever their subject, is always the same. The old masters were artists as well as churchmen, and knew how to adapt their somewhat unresponsive material to the more obvious contrasts of the text; and in actual performance a much wider latitude in respect to _nuance_ and change of speed was permitted than could be indicated in the score. We know, also, that the choristers were allowed great license in the use of embellishments, more or less florid, upon the written notes, sometimes improvised, sometimes carefully invented, taught and handed down as a prescribed code, the tradition of which, in all but a few instances, has been lost. But the very laws of the Gregorian modes and the strict contrapuntal system kept such excursions after expression within narrow bounds, and the traditional view of ecclesiastical art forbade anything like a drastic descriptive literalism.